Method and apparatus for treating magnetic cores and windings

ABSTRACT

A device utilizing high-energy electrical pulses for positioning coil windings in core slots of the stator of a dynamoelectric machine, for applying mechanical force to position the end turns of such windings, and for pounding stator cores to reduce core loss comprises a top and bottom plate positioned by tie rods which have nuts for adjusting the separation distance of the plates, a flat coil winding overlying the bottom plate, and a metal plate overlying the flat coil. When the device is used to pound stator cores a stator is placed on the metal plate and a high-energy electric pulse is sent through the flat coil. This creates a strong transient magnetic field which causes the metal plate to snap the stator against the top plate of the device. When the device is used to position coil windings in the stator, forming blocks having annular grooves to fit the end turns of stator coils are positioned on the metal plate and top plate and a stator with loose coil windings placed therebetween. The coil windings themselves are then subjected to a high-energy pulse, or series of such pulses. This compacts the windings within the stator core slots and draws the end turns down toward the stator core. The forming blocks are then positioned against the end turns and the flat coil is energized by a high-energy electrical pulse, or series of such pulses. The transient magnetic field created thereby causes the metal plate to move toward the top plate thereby squeezing the stator and end turns between the two forming blocks. The mechanical working of the end turns produced by this squeezing positions them firmly in the desired relationship to the stator core.

Unite States Patent [72] Inventor Norman A. Bender Fort Wayne, Ind. [21]Appl. No. 803,395 [22] Filed Feb. 28, 1969 [45] Patented Dec. 21, 1971[73] Assignee General Electric Company [54] METHOD AND APPARATUS FORTREATING MAGNETIC CORES AND WINDINGS 11 Claims, 3 Drawing Figs.

[52] US. Cl 29/596, 29/203 L, 29/205 R, 29/205 D, 29/421, 29/609,225/103 [51] lnt.Cl ....H02k 15/00 [50] Field of Search 29/596, 598,609, 205, 203 L, DIG. 46, 421; 225/103; 335/258 [56] References CitedUNlTED STATES PATENTS 1,762,017 6/1930 Grenzer 29/203 X 1,813,802 7/1931Hildebrand 29/609 UX 2,876,429 3/1959 Noztitz 335/258 X 2,980,157 4/1961Rediger 29/205 X 3,421,208 1/1969 Larsen et al. 29/609 PrimaryExaminer-John F. Campbell Assistant Examiner-Carl E. HallAttorneys-Allard A. Braddock, Harold J. Holt, John M.

Stoudt, Frank L. Neuhauser and Oscar B. Waddell ABSTRACT: A deviceutilizing high-energy electrical pulses for positioning coil windings incore slots of the stator of a dynamoelectric machine, for applyingmechanical force to position the end turns of such windings, and forpounding stator cores to reduce core loss comprises a top and bottomplate positioned by tie rods which have nuts for adjusting theseparation distance of the plates, a flat coil winding overlying thebottom plate, and a metal plate overlying the flat coil. When the deviceis used to pound stator cores a stator is placed on the metal plate anda high-energy electric pulse is sent through the flat coil. This createsa strong transient magnetic field which causes the metal plate to snapthe stator against the top plate of the device. When the device is usedto position coil windings in the stator, forming blocks having annulargrooves to fit the end turns of stator coils are positioned on the metalplate and top plate and a :stator with loose coil windings placedtherebetween. The coil windings themselves are then subjected to ahigh-energy pulse, or series of such pulses. This compacts the windingswithin the stator core slots and draws the end turns down toward thestator core. The forming blocks are then positioned against the endturns and the flat coil is energized by a high-energy electrical pulse,or series of such pulses. The transient magnetic field created therebycauses the metal plate to move toward the top plate thereby squeezingthe stator and end turns between the two forming blocks.- The mechanicalworking of the end turns produced by this squeezing positions themfirmly in the desired relationship to the stator core.

PATENTED DELZI ma Wan/j Mayra '4 TTORNEV .3 6 POWER SUPPLY METHOD ANDAPPARATUS FOR TREATING MAGNETIC CORES AND WINDINGS BACKGROUND OF THEINVENTION When a magnetic coil is subjected to a high-energy electricpower impulse the resulting interaction of current and magnetic fieldscreates a force which may be utilized to achieve desired ends. InLinkous U.S. Pat. No. 3,333,329, which is assigned to the same assigneeas the present invention, such an impulse was used to pack coil windingsin core slots of the stator of a dynamoelectric machine. In Gibbs andRushing application Ser. No. 426,991, filed Jan. 21, 1965, which issuedJan. 14, 1969 as U.S. Pat. No. 3,421,209, and is also assigned to thesame assignee as the present application, a magnetic field produced by ahigh-energy impulse was utilized to separate the laminations of a statorcore thereby reducing the electrical losses caused by interlaminatemetallic bonds established during fabrication.

BRIEF SUMMARY OF THE INVENTION AND OF THE DRAWING One object of thepresent invention is to provide a new and improved device for compactingcoils and accomplishing a reduction of stator core losses.

It is another object of the present invention to provide a new andimproved apparatus for reducing the core loss of a laminated magneticcore.

It is still another object of the present invention to provide a new andimproved method of reducing the core loss of a laminated magnetic core.

It is yet another object to provide a new and improved method ofpositioning one or more winding coils of a stator and effecting areduction of stator core losses.

It is a still further object of the present invention to provide new andimproved apparatus for positioning at least selected portions of awinding supported by a wound laminated magnetic core relative to thecore.

The present invention preferably is embodied in one form in to a deviceor fixture in which a stator core may be mounted and force applied tospread'the laminations or in which, a stator core with windings in placemay be mounted and the windings may be positioned according to themethod described in the aforementioned Linkous U.S. Pat. No. 3,333,329.After application of the Linkous method, the end turns of the statorcoil may be finally placed in position by mechanical working resultingfrom the application of a highenergy electrical impulse and theoperation of one or more forming blocks.

Apparatus embodying the invention in a preferred form includes a deviceor fixture having a bottom plate and top plate spaced somewhat from eachother and held in position by tie rods. The bottom or base plate has aflat electrical coil mounted thereon. Overlying the coil is a metalplate which is free to move with respect to the coil. Circuit controlterminals may be conveniently positioned on an exterior surface of thedevice to provide quick switching between circuits.

The operation of the device will be readily understood from the drawingin which:

FIG. I is a front view partly in section showing a device or fixtureembodying the invention;

FIG. 2 is a top view partly in section showing the use of formingblocks; and

FIG. 3 is a schematic circuit diagram illustrating the control circuit.

DETAILED DESCRIPTION Referring to the drawing, the illustrated device orfixture provides a means for accommodating a laminated magnetic core andcomprises a base or bottom plate and a top plate Ill, normally composedof metal, which are held in spacedapart position by a number of tie rods12. Each of the tie rods 12 has a tightening nut 13 and an adjusting nut14, the latter serving to vary the spacing between the bottom plate 10and top plate II.

A flat electrically energizable stationary magnetic coil 16, sometimesreferred to as a pancake coil, is mounted on top of the bottom plate IIIand provides means for producing a magnetic field upon application of anenergy impulse thereto. While not absolutely necessary it is desirableto protect the coil I6 by positioning it in a plate I5 of electricallynonconducting material such as plastic laminate. Over-lying the coil I6is a member or plate I9 composed of a metal such as copper or aluminum.The plate I9, which is positioned between the guide members 26, is notfastened to the coil I6 or plate I5 and is, therefore, free to move inan upward direction.

A series of terminals 22, 23, and 2d are mounted on the bottom plateIII. A single pole double throw switch 25 is manually set to select acircuit through the terminals 22 and 23 which supply a stator winding 28or the terminals 23 and 2A which supply the pancake coil I6. Theseterminals are incorporated in a circuit which provides a high-energyelectrical impulse. A source of such impulses may be provided by thedischarge of a capacitor bank. One suitable source is described inLinkous U.S. Pat. No. 3,333,329 which patent is incorporated herein byreference. In view of the fact that such circuits are not a part of thisinvention, they are not described in detail herein. Conventional powersources can supply impulses of several thousand joules at severalthousand volts. In selecting the impulse to be used the limiting factoris the energy level at which coil insulation or the coil metal itselfwill be damaged. in order to avoid serious damage, the normal practiceis to provide a series of impulses of increasing magnitude.

The use of the device shown in FIGS. I and 2 for pounding stator corelaminations will now be described. A stator core such as that shown at27 in FIG. I is positioned directly on a surface defined at least partlyby the plate I9 which thus is sandwiched between the coil I6 and one endof the stator 27. A high-energy impulse is then sent and generatedthrough coil 16. This produces a transient magnetic field, the force ofwhich impels or snaps the plate I9 in the direction of the stationarytop plate or member II. The stator core 27 strikes the surface of thetop plate II with a force proportional to the magnitude of the impulse.This magnitude is adjusted to provide the minimum impulse which caneffectively sever interlaminate metallic bonds. While the stator core isdescribed as striking the top plate II which is at least slightly spacedfrom the top end face of the stator as viewed in FIG. I, it is desirableto mount a separate bang plate (not shown) on the underside of the topplate II so as to protect this member from damage from repeated poundingby stator cores.

In order to position the end turns of coils 28, the apparatus isequipped with coil-end turn forming members in the forms of a bottomcoil-end turn forming block 17 and a top coil-end turn forming block 13.These forming blocks are preferably composed of a relatively softmaterial such as a laminated plastic and are equipped with annulargrooves 20 which are shaped to fit the end turns of the coil 28. Meansfor maintaining alignment of the core relative to the block I7 isillustrated as a nonmagnetic plug or cylindrical structure 21 composedof copper, aluminum or similar metal and is positioned within thealigned center apertures of the blocks I7 and I8 as illustrated to serveas a positioning means for mounting a stator core 27 in the device andaid in positioning or throwing back windings as described in RushingU.S. Pat. No. 3,333,328. As may be seen in FIG. 1, the top plate Il maybe U-shaped in order to allow easy positioning and removal of the statorcore 27.

Referring particularly to FIG. 3, a lead 3I from a power supply 36 isconnected to the flat coil I6 and the stator winding 28. The other endof the flat coil I6 is: connected to the terminal 24 and the other endof the stator winding 28 is arranged for easy connection to the terminal22. The terminals 22 and 24 are selectively connectable by means of theswitch 25 through a lead 32 to the power supply 36 to complete theenergizing circuit.

The operation of the device will now be described with reference to allof its functions. Initially, the forming blocks I7 and 18 are removedand a stator core 27 without a coil winding is mounted within thedevice. The single pole switch 25 is closed across the terminals 23 and24. The power supply is now set to the energy level which has proved tobe the minimum satisfactory to break the interlaminate metallic bonds ofthe particular stator core 27 which is the workpiece. A high-energyimpulse or surge of electrical current is now passed through the coil16. The magnetic field produced by thisimpulse impels the metal plate 19and stator core toward the top plate 11. The impact of the laminatedstator core 27 on the top plate 11 breaks the interlaminate bonds of thestator core 27, thereby loosening the stator core laminations to reducethe electrical core losses as will be understood by those skilled in theart. The stator core is then removed from the device and placed in aseparate machine which loosely inserts the coil winding 28 in the slotsof the stator core. The forming block 17 is now placed in the device asshown and the stator including the winding is inserted over thenonmagnetic member 21 so as to be positioned thereby and supported onthe forming block 17; and the forming block 18 is placed thereover. Oneend of the winding 28 is connected to the terminal 22 and the other endis connected to the power supply lead 31. The single pole switch 25 isthen operated to close a circuit through the terminals 22 and 23. Ahigh-energy impulse is now sent through the circuit to generate a surgeof electrical current in the conductor turns of the stator coil.Electrical magnetic forces resulting from this impulse produce a forceon the winding 28 which tends to seat the winding deep within the coreslots of the stator core 27 and thus compact the winding coils and alsotends to impel or draw the end turns toward the stator core. In order tominimize the stress on the insulation of the winding 28, it is desirableto deliver several impulses of mounting intensity over spaced intervalsof time as described in the Linkous patient aforementioned.

The single pole switch 25 is now returned to its position where itconnects the terminals 23 and 24. A high-energy impulse is sent throughthe flat coil 16 in the same manner as when the stator core 27 was beingtreated to break the interlaminate metallic bonds. Now, however, thepresence of the soft-surface forming blocks 17 and 18 results in theapplication of mechanical squeezing to the end turns of the winding 28.In order to minimize the risk of damage to the insulation of thewindings, this part of the process may be broken into several impulsesof mounting intensity delivered at spaced intervals of time. While asingle device has been described as performing both a delaminating and acoil-positioning function, it will be understood that in practice thosefunctions will usually be performed by two separate devices.

In order to help position and brace the parts, the apparatus illustratedhas been provided with base numbers 26 on each side of the device.However, these, as well as other parts, may be omitted or alteredwithout departing from the spirit of the invention. For instance, it isnot necessary that the distance between the bottom plate and the topplate 11 be variable and other means than the tie rods 12 can be used tohold the parts in their proper orientation. Accordingly, it is believedthat the invention should be limited in scope only as may benecessitated by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. A device for compacting coils and loosening stator core laminationsto reduce stator core losses comprising: spaced top and bottom plates;an electrically energizable stationary coil mounted in a plate composedof electrically noneonducting material overlying said bottom plate; ametallic plate overlying said coil, a bottom coil-end turn forming blockfor forming the end turns adjacent one end of a wound laminated coreoverlying the metallic plate, and a top coil-end turn forming block forforming the end turns adjacent the other end of the wound laminated corecontacting the top plate, whereby energizing said coil creates amagnetic field, the force of which impels said metallic plate towardsaid top plate.

2. A device as claimed in claim l in which the coil-end turn formingblocks have aligned center apertures and a nonmagneticstator-positioning and wirepositioning member is mounted in the centeraperture of the bottom coil-end turn forming block.

3. A method of selectively (l) loosening laminations of a stator core toreduce stator core losses and (2) positioning the coil of the statorcomprising: positioning a stator, a movable plate, and a stationary coilwith the movable plate sandwiched between the coil and one end of thestator; positioning a stationary plate spaced slightly from the otherend of the stator; generating at least one surge of electrical currentin the sta tionary coil such that the movable plate impels the statoragainst the stationary plate to loosen the laminations forming thestator core; positioning a coil-end turn forming block at each end ofthe stator; generating at least one surge of electrical current in theconductor turns of the stator coil such that the end turns of the statorcoil are impelled toward the stator core; and generating at least onesurge of electrical current through the stationary coil to create amagnetic field, the force of which impels the movable plate toward thestator to squeeze the stator coil end turns between the coil-end turnforming blocks.

4. Apparatus for reducing the core loss of a laminated magnetic core,said apparatus comprising means for accommodating a laminated magneticcore, said means including first and second members spaced apart foraccommodating the laminated magnetic core therebetween, a first one ofsaid members defining at least a part of a first surface for engagementwith a first end of the laminated magnetic core, a second one of saidmembers defining at least a part of a second surface for engagement bythe laminated magnetic core at least when the core is impelledthereagainst by the first member, and means adjacent said first memberfor producing a magnetic field upon application thereto of an energyimpulse preselected to impel by the force of said magnetic field saidfirst member toward said second member with a force sufficient to impactthe laminated magnetic core against the second surface, whereby thelaminated magnetic core is impelled by the first member and impactsagainst the second member as the magnetic field is produced andinterlaminate bonds within the laminated magnetic core are broken toachieve a reduction in electrical losses of the laminated magnetic core.7

5. The apparatus of claim 4 wherein said means for producing a magneticfield comprises an electrically energizable stationary coil, said secondmember is supported a predetermined distance from said stationary coil,and said first member is disposed between said stationary coil and saidsecond member.

6. The apparatus of claim 4 further including an apparatus base andmeans for supporting said second member a preselected distance from thebase; and wherein the means for producing a magnetic field comprises anelectrically energizable stationary coil overlying the base andsupported in fixed relation relative thereto, said first member beingdisposed between said stationary coil and said second member.

7. Apparatus for positioning selected portions of a winding supported bya wound laminated magnetic core relative to the core, the apparatuscomprising a stationary electrically energizable coil, means forsupporting the electrically energizable coil, support means forsupporting a wound laminated magnetic core, core positioning means forpositioning a wound laminated magnetic core relative to the supportingmeans; and a first coil-end turn forming block for forming the end turnportions of a winding at one end of a wound laminated core; saidelectrically energizable coil producing a magnetic field uponapplication thereto of a preselected electrical energy impulse, theforce of said magnetic field effecting movement of a laminated coretoward the coil-end turn forming block whereby the end turn portions ofthe winding at the one end of the wound laminated core are pressed andformed against the coil-end turn forming block.

8. The apparatus of claim 7 wherein said supporting means comprises asecond coil-end turn forming block for forming the end turn portions ofa winding at the other end of the wound laminated core and wherein saidsupporting means are impelled toward the first coil-end turning blockupon energization of the energizable coil; whereby the end turn portionsof the winding at the other end of the wound laminated core are pressedand formed by the second coil-end turn forming block, said secondcoil-end turn forming block moving toward the first coil-end turnforming block upon energization of said energized coil.

9. The apparatus of claim 7 further including switch rneans forselectively connecting said energizable coil and the winding supportedby the wound core to an electrical energy impulse source.

10. A method of reducing the core loss of a laminated magnetic corecomprising the steps of positioning the magnetic core adjacent to afirst member engageable with the magnetic core, producing a magneticfield in the vicinity of the first member and thereby impelling by theforce of said magnetic field the first member and magnetic core toward asecond member, and breaking interlaminate bonds within the magnetic coreto achieve a reduction in electrical losses of the laminated magneticcore by impacting the magnetic core against the second member.

11. A method of .forming at least a portion of the coil-end turnportions of a winding supported on a laminated magnetic core against acoil-end turn forming :member, said method comprising the steps ofpositioning the magnetic core adjacent a first member engageable withthe magnetic core, producing a magnetic field in the vicinity of thefirst member, and thereby impelling by the force of said magnetic fieldthe first member and magnetic core toward a coil-end turn forming memberand causing the coil-end turn portions of the winding adjacent one endof the laminated core to be formed against the coil-end turn formingmember.

1. A device for compacting coils and loosening stator core laminationsto reduce stator core losses comprising: spaced top and bottom plates;an electrically energizable stationary coil mounted in a plate composedof electrically nonconducting material overlying said bottom plate; ametallic plate overlying said coil, a bottom coil-end turn forming blockfor forming the end turns adjacent one end of a wound laminated coreoverlying the metallic plate, and a top coil-end turn forming block forforming the end turns adjacent the other end of the wound laminated corecontacting the top plate, whereby energizing said coil creates amagnetic field, the force of which impels said metallic plate towardsaid top plate.
 2. A device as claimed in claim 1 in which the coil-endturn forming blocks have aligned center apertures and a nonmagneticstator-positioning and wire-positioning member is mounted in the centeraperture of the bottom coil-end turn forming block.
 3. A method ofselectively (1) loosening laminations of a stator core to reduce statorcore losses and (2) positioning the coil of the stator comprising:positioning a stator, a movable plate, and a stationary coil with themovable plate sandwiched between the coil and one end of the stator;positioning a stationary plate spaced slightly from the other end of thestator; generating at least one surge of electrical current in thestationary coil such that the movable plate impels the stator againstthe stationary plate to loosen the laminations forming the stator core;positioning a coil-end turn forming block at each end of the stator;generating at least one surge of electrical current in the conductorturns of the stator coil such that the end turns of the stator coil areimpelled toward the stator core; and generating at least one surge ofelectrical current through the stationary coil to create a magneticfield, thE force of which impels the movable plate toward the stator tosqueeze the stator coil end turns between the coil-end turn formingblocks.
 4. Apparatus for reducing the core loss of a laminated magneticcore, said apparatus comprising means for accommodating a laminatedmagnetic core, said means including first and second members spacedapart for accommodating the laminated magnetic core therebetween, afirst one of said members defining at least a part of a first surfacefor engagement with a first end of the laminated magnetic core, a secondone of said members defining at least a part of a second surface forengagement by the laminated magnetic core at least when the core isimpelled thereagainst by the first member, and means adjacent said firstmember for producing a magnetic field upon application thereto of anenergy impulse preselected to impel by the force of said magnetic fieldsaid first member toward said second member with a force sufficient toimpact the laminated magnetic core against the second surface, wherebythe laminated magnetic core is impelled by the first member and impactsagainst the second member as the magnetic field is produced andinterlaminate bonds within the laminated magnetic core are broken toachieve a reduction in electrical losses of the laminated magnetic core.5. The apparatus of claim 4 wherein said means for producing a magneticfield comprises an electrically energizable stationary coil, said secondmember is supported a predetermined distance from said stationary coil,and said first member is disposed between said stationary coil and saidsecond member.
 6. The apparatus of claim 4 further including anapparatus base and means for supporting said second member a preselecteddistance from the base; and wherein the means for producing a magneticfield comprises an electrically energizable stationary coil overlyingthe base and supported in fixed relation relative thereto, said firstmember being disposed between said stationary coil and said secondmember.
 7. Apparatus for positioning selected portions of a windingsupported by a wound laminated magnetic core relative to the core, theapparatus comprising a stationary electrically energizable coil, meansfor supporting the electrically energizable coil, support means forsupporting a wound laminated magnetic core, core positioning means forpositioning a wound laminated magnetic core relative to the supportingmeans; and a first coil-end turn forming block for forming the end turnportions of a winding at one end of a wound laminated core; saidelectrically energizable coil producing a magnetic field uponapplication thereto of a preselected electrical energy impulse, theforce of said magnetic field effecting movement of a laminated coretoward the coil-end turn forming block whereby the end turn portions ofthe winding at the one end of the wound laminated core are pressed andformed against the coil-end turn forming block.
 8. The apparatus ofclaim 7 wherein said supporting means comprises a second coil-end turnforming block for forming the end turn portions of a winding at theother end of the wound laminated core and wherein said supporting meansare impelled toward the first coil-end turning block upon energizationof the energizable coil; whereby the end turn portions of the winding atthe other end of the wound laminated core are pressed and formed by thesecond coil-end turn forming block, said second coil-end turn formingblock moving toward the first coil-end turn forming block uponenergization of said energized coil.
 9. The apparatus of claim 7 furtherincluding switch means for selectively connecting said energizable coiland the winding supported by the wound core to an electrical energyimpulse source.
 10. A method of reducing the core loss of a laminatedmagnetic core comprising the steps of positioning the magnetic coreadjacent to a first member engageable with the magnetic core, producinga magnetic field in the vicinity of the first member aNd therebyimpelling by the force of said magnetic field the first member andmagnetic core toward a second member, and breaking interlaminate bondswithin the magnetic core to achieve a reduction in electrical losses ofthe laminated magnetic core by impacting the magnetic core against thesecond member.
 11. A method of forming at least a portion of thecoil-end turn portions of a winding supported on a laminated magneticcore against a coil-end turn forming member, said method comprising thesteps of positioning the magnetic core adjacent a first memberengageable with the magnetic core, producing a magnetic field in thevicinity of the first member, and thereby impelling by the force of saidmagnetic field the first member and magnetic core toward a coil-end turnforming member and causing the coil-end turn portions of the windingadjacent one end of the laminated core to be formed against the coil-endturn forming member.